<?php

namespace backend\utils;

class Jwt
{
    //头部
    private static $header = array(
        'alg' => 'HS256', //生成signature的算法
        'typ' => 'JWT'    //类型
    );

    //使用HMAC生成信息摘要时所使用的密钥
    private static $key = 'linghang_training_key';


    /**
     * 获取jwt token
     * @param array $payload jwt载荷   格式如下非必须
     * [
     *  'iss'=>'jwt_admin',  //该JWT的签发者
     *  'iat'=>time(),  //签发时间
     *  'exp'=>time()+7200,  //过期时间
     *  'nbf'=>time()+60,  //该时间之前不接收处理该Token
     *  'sub'=>'www.admin.com',  //面向的用户
     *  'jti'=>md5(uniqid('JWT').time())  //该Token唯一标识
     * ]
     * @return bool|string
     */
    public static function getToken(array $payload)
    {
        if (is_array($payload)) {
            $base64header = self::base64UrlEncode(json_encode(self::$header, JSON_UNESCAPED_UNICODE));
            $base64payload = self::base64UrlEncode(json_encode($payload, JSON_UNESCAPED_UNICODE));

            $token = $base64header .
                '.' . $base64payload .
                '.' . self::signature($base64header . '.' . $base64payload, self::$key, self::$header['alg']);
            return $token;
        } else {
            return false;
        }
    }


    /**
     * 验证token是否有效,默认验证exp,nbf,iat时间
     * @param string $Token 需要验证的token
     * @return bool|string
     */
    public static function verifyToken(string $Token)
    {
        $tokens = explode('.', $Token);
        if (count($tokens) != 3)
            return false;

        list($base64header, $base64payload, $sign) = $tokens;

        //获取jwt算法
        $base64decodeheader = json_decode(self::base64UrlDecode($base64header), JSON_OBJECT_AS_ARRAY);
        if (empty($base64decodeheader['alg']))
            return false;

        //签名验证
        if (self::signature($base64header . '.' . $base64payload, self::$key, $base64decodeheader['alg']) !== $sign)
            return false;

        $payload = json_decode(self::base64UrlDecode($base64payload), JSON_OBJECT_AS_ARRAY);
        /**
         * $payload eg:
         *
         * Array
         * (
         *      [uuid] => f1967cab-99cd-11ec-bd6e-02420a39000c
         *      [username] => linghang
         *      [real_name] => 领航1
         *      [tel] => 13120345353
         *      [school_id] => 8c626563-90a8-35c4-97dd-6a9ace55c351
         *      [school_name] => 北京信息职业技术学院
         *      [school_code] => 10857
         *      [roles] => admin,teacher,expert
         *      [iss] => dataCenter
         *      [iat] => 1646360231
         *      [exp] => 1646367431
         *      [sub] => ffcbd1b6-9ab6-11ec-bd6e-02420a39000c
         *      [jti] => 22be11cc85df4832581f4ebb2cdb8d58
         * )
         */

        //签发时间大于当前服务器时间验证失败
        if (isset($payload['iat']) && $payload['iat'] > time())
            return false;

        //过期时间小宇当前服务器时间验证失败
        if (isset($payload['exp']) && $payload['exp'] < time())
            return false;

        //该nbf时间之前不接收处理该Token
        if (isset($payload['nbf']) && $payload['nbf'] > time())
            return false;

        return $payload;
    }


    /**
     * base64UrlEncode   https://jwt.io/  中base64UrlEncode编码实现
     * @param string $input 需要编码的字符串
     * @return string
     */
    private static function base64UrlEncode(string $input)
    {
        return str_replace('=', '', strtr(base64_encode($input), '+/', '-_'));
    }

    /**
     * base64UrlEncode  https://jwt.io/  中base64UrlEncode解码实现
     * @param string $input 需要解码的字符串
     * @return bool|string
     */
    private static function base64UrlDecode(string $input)
    {
        $remainder = strlen($input) % 4;
        if ($remainder) {
            $addlen = 4 - $remainder;
            $input .= str_repeat('=', $addlen);
        }
        return base64_decode(strtr($input, '-_', '+/'));
    }

    /**
     * HMACSHA256签名   https://jwt.io/  中HMACSHA256签名实现
     * @param string $input 为base64UrlEncode(header).".".base64UrlEncode(payload)
     * @param string $key
     * @param string $alg 算法方式
     * @return mixed
     */
    private static function signature(string $input, string $key, string $alg = 'HS256')
    {
        $alg_config = array(
            'HS256' => 'sha256'
        );
        return self::base64UrlEncode(hash_hmac($alg_config[$alg], $input, $key, true));
    }

    public static function AddArr($arr)
    {
        $key = [
            'iss' => 'data_center',  //该JWT的签发者
            'iat' => time(),  //签发时间
            'exp' => time() + 3600 * 48,  //过期时间
            'nbf' => time() + 60,  //该时间之前不接收处理该Token
            'sub' => 'beike',  //面向的用户
            'jti' => md5(uniqid('JWT') . time())  //该Token唯一标识
        ];
        return array_merge($key, $arr);
    }

    public static function ReturnData($code, $msg, $data = [], $totalCount = 0)
    {
        $data = [
            'code' => $code,
            'msg' => $msg,
            'data' => $data,
            'totalCount' => $totalCount,
        ];
        \Yii::$app->end(json_encode($data));
    }
}
